Filament connection for electric lamps



Jan. 11, 1944.

L. G. LEIGHTQN FILAMENT CONNECTION FOR ELECTRIC LAMPS Filed June 19', 1943 Leroy G. Lejgb hfon,

. His Air'itor'neg lnven+ov z .T: -MWWM@ l M a w H Patented Jan. 11, 1944 2,338,855 murmur CONNECTION ron Emcmc LAMPS Leroy G. Leighton, Cleveland, Ohio, assimor to General Electric Company, a corporation of New York.

Application rune 19, 1943, Serial No. 491,434

My invention relates in general to electric i ncandescent lamps and similar devices, andmore particularly to high wattage lamps and devices.

Still more particularly my invention relates to an improved joint or connection between the filament and leading-in conductors of suchdevices.

In high wattage incandescent lamps, it is necessary to employ side leading-in conductors or supports made of a metal which will withstand the heat radiated by the lamp filament during operation. At present, molybdenum is used for such purpose because it possesses the necessary heat-resisting properties.

Where the connection 01' the tungsten filament to such molybdenum lead-in conductors or side supports involves a welded joint, the welding operation tends to make the tungsten filament and the molybdenum lead-in conductors brittle at points adjacent the weld so that they are liable to break off at such points if the lamp is jarred.

One object of my invention is to provide an improved form of joint or connection between the filament and leading-in conductors of electric incandescent lamps and similar devices which Joint provides a good mechanical and electrical connection of the filament to the leading-in conductors.

Another object of my invention is to provide a a strong joint between the filament and leadingin conductors of electric incandescent lamps of the high wattage type.

Still another object of my invention is to provide a joint between a tungsten lamp filament and a molybdenum leading-in conductor which can be formed without embrittling either the tungsten filament or the molybdenum conductor at points adjacent the joint so as to render them mechanically weak and therefore liable to breakage at such points.

A feature of the invention is the use of a metal a portion of the filament Joint; and Fig. 4 is a view similar to Fig. 3 01' a modified form 01' my invention.

Referring to the drawing, the lamp there shown comprises a glass bulb l0 having a base construction 01' the type shown and claimed in U. S. Patent No. 2,098,080D. K. Wright, and consisting of. a pressed glass cup portion II to which is sealed 8. pair oi metal contact terminal devices or prongs l2, l2 which serve for mounting the lamp and for conducting current thereto. Secured to the metal terminals [2, I2 and extending into the bulb III in parallel relation are a pair of rigid metal leading-in conductors or supports l3. l3. The inner ends of the said conductors l3, l3 are bent outwardly away from each other to form laterally-extending portions i l, ll the outer ends oi which are provided with hooks or eyes I 5, [5. The conductors l3, l3 may be made of nickelplated iron and are provided with rigid rod or wire extensions i6, iii of molybdenum which are securely fastened to the conductors l3, l3 and extend parallel to one another on opposite sides of the tungsten filament H. The molybdenum extensions l6, l6 extend through the loops l5, I5 which are pinched tightely onto the said extensions. The lower ends of the extensions l6, l8

are bent toward one another to form laterallyextending portions l8, l8 which are spot-welded connector clip or lug, one end of which is pinched onto the leading-in conductor and the other end of which is pinched around a slip-over coil on the end leg of the filament.

Further objects and advantages of my inven tion will appear from the following description oi a species thereof and. from the accompanying drawing in which:

Fig- 1 is an elevation of an electric incandescent lamp having a filament Joint construction comprising my invention; Fig. 2 is a perspective view, on an enlarged scale, of the filament joint of the lamp shown in Fig. 1; Fig. 3 is an elevation, partly in section and on an enlarged scale, of

to the conductors i3, i3.

The leading-in conductors are held in rigid spaced relation by upper and lower insulating bridges or cross bar members [9, 20, respectively, of suitable insulating material. such as glass, which extend between and are secured to the leading-in conductors by short fastening wires 2|. The fastening wires 2| for the upper bridge member is may be spot-welded to short tip extensions 2.2, 22 of nickel-plated iron which are butt-welded to the molybdenum side rods or concluctor extensions l8, IS. The fastening wires 2i for the lower bridge member 20 may be spotwelded to the nickel-plated iron conductors l 3, (3.

The filament I i is of the high wattage type. the particular filament illustrated being oi! the type shown in U. S. Patent No. 2,288,499--I. H. Van Horn and comprising a plurality of coiled segments successive ones of which are arranged triangularly in a helix defining a triangular prism extending transversely of and between the conductor extensions l6, 16. The coiled segments are joined by bight portions 23, and the filament is supported in place by means of a plurality of upper and lower anchor wires 24 having hooked ends engaging the bights 23 and their other ends rigidly secured to the insulating bridge members I8, 23, as by embedding therein.

In accordance with the invention, each end of the filament i1 is provided with a straight or uncoiled end section or leg portion 25 (Figs. 2-3) over which is slipped a coil 25 preferably of molybdenum or tungsten wire. The said slipover coil 28 is wound with a fairly close pitch, 1. e., closely coiled, and is preferably made Just large enough in diameter to fit more or'less snugly around the filament leg 25. 1 Each end of the filament I1 is connected'to the adjacent molybdenum side rod or conductor extension l8 by a connector or clip 21 of a metal, preferably nickel, which will satisfactorily withstand the heat attending lamp operation. The connectors or clips 21 are made of strip metal of a suitable width (in the instance shown around A or so) and are each formed with hooks or eyes 28 at their opposite ends which are tightly pinched or clamped one around the slip-over coil 26 on the filament leg 25 and the other around the adjacent conductor extension It by means of a pinching tool or pliers having suitably shaped pinching laws. The mechanical attachment of the filament I1 t the leading-in conductors by the connector clips 21 eliminates all welded joints between the tungsten filament and the molybdenum conductor extensions l8, l8 together with all the disadvantages which would result from the welding operation.

In the modification shown in Fig. 4, the slipover coil 29 differs from the coil 28 in Figs. 1-3 in that it is wound with a widely open. center section 30 instead of being wound with a uniform pitch throughout as in the case of the coil 28. This opened center section 30 insures a firmer attachment or clamping of the slip-over coil 28 onto the filament leg 25 so as to prevent its slipping off the end thereof, and for that reason enables the use of slip-over coils which are wound to a larger inside diameter and which, therefore, fit more or less loosely over the filament leg 25.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. In an electric incandescent lamp, the combination of a conductive lead, a filament having an end portion, a slip-over coil on the said end portion of said filament, and a metal connector having one end secured to said conductive lead and the other end iormed with a book which is tightly clamped around the said slip-over coil and the enclosed filament end portion.

2. In an electric incandescent lamp, the combination of a conductive lead, a filament having an end portion adjacent to but spaced from the said conductive lead, a slip-over coil on the said end portion of said filament, and a metal connector extending between the said conductive lead and the filament end portion, said metal connector having one end clampedto said conductive lead and the other end clamped around the said slip-over coil and the enclosed filament end portion.

3. In an electric incandescent lamp, the combination of a molybdenum lead-in conductor, a tungsten filament having an end portion adjacent to but spaced from the said lead-in conductor, a slip-over coll on the said end portion of said filament, and a metal connector extending between the said lead-in conductor and the filament end portion, said metal connector having one end clamped to saidlead-in conductor and the other end clamped around the said slip-'- over coil and the enclosed filament end portion.

4. In an electric incandescent lamp, the combination of a conductive lead, a filament having an uncoiled end portion, a wire slip-over'coil on the said end portion of said filament, and a metal connector strip having spaced hooks one of which is tightly clamped to said conductive lead and the other of which is tightly clamped around the said slip-over coil and the enclosed filament end portion.

5. In an electric incandescent lamp, the comblnation of a conductive lead. a filament having an uncoiled end portion, a wire slip-over coil on the said end portion of said filament and having closely-coiled end sections separated by an opencoiled center section, and a metal connector strip having one end secured to said conductive lead and the other end formed with a hook which is tightly clamped around the open-coiled center section of the slip-over coil to securely fasten said coil in place on the uncoiled wire end portion of said filament.

, LEROY G. LEIGHTON. 

